Milligrams, micrograms and the units that are not weights
A factor of a thousand, a factor that is not a factor at all, and where the decimal point actually goes.
Most of what is sold in this market is sold by weight, and weight is the easy case. The confusion starts where a number on a label is not a weight at all.
The thousand
A milligram is a thousand micrograms, and a gram is a thousand milligrams. Everything on this shelf is labeled in milligrams. Analytical literature often reports small quantities in micrograms, so the same mass can appear as two numbers a thousand apart.
Units that are not weights
An international unit measures activity rather than mass. It is defined per substance by an agreed biological standard, so a unit of one thing and a unit of another have no set relationship to each other and no set relationship to milligrams. There is no universal conversion.
Products in this catalog are labeled by mass. International units turn up in the surrounding literature, and a figure in international units cannot be compared to a mass without the specific standard for that substance.
Concentration is a third thing
A concentration is not a quantity. A certificate reports mass. Concentration depends on how a solution was prepared and is not a property of the vial.
Common questions
How many micrograms are in a milligram?
A milligram is a thousand micrograms, and a gram is a thousand milligrams. Products in this catalog are labeled in milligrams, while analytical literature often reports small quantities in micrograms, so the same mass can appear as two numbers a thousand apart.
Is an international unit a measure of weight?
No. An international unit measures activity, not mass. It is defined per substance by an agreed biological standard, so a unit of one substance has no set relationship to a unit of another and no set relationship to milligrams. There is no universal conversion.
Is a concentration the same thing as the mass on a certificate?
No. A concentration is not a quantity. A certificate reports mass, while concentration depends on how a solution was prepared and is not a property of the vial. That makes it a third thing, separate from both weights and international units.
Why do two sources give figures for the same material that differ by a thousand?
It is usually a difference of unit, since a milligram is a thousand micrograms and the same mass can be written either way. When two sources disagree by exactly a thousand, neither is wrong about the chemistry, and the unit is the first thing to compare.
For laboratory research use only. Not a drug, not a supplement, and nothing here is a claim about what any of this material does in a person or an animal.
